Laser diode wafers are presently cleaved into useful devices for emitting light, for example, for coupling to optical fibers. Such devices have a plurality of emitters on a facet defined along the cleaved edge. Prior to cleavage, the laminated structure which defines the facet is formed on the top planar surface of a wafer. The wafer is then cleaved into a plurality of laser diode bars, the cleaved surface being planar and normal to the top surface of the wafer.
A mirror finish is required of the cleaved surface and the optimal device performance depends on the quality of that surface. But the quality of the surface depends on the thickness of the (precleaved) wafer. The thicker the wafer, the more defects are seen on the light emitting surface. At the present time, the ratio between the vertical dimension (thickness) of the wafer and the separation between adjacent cleavage planes in the wafer has been established in the art as approximately 3/4.